Hi. I want to use the Arduino Uno to build a Spark-Ignition-System.I'd like to use a common ignition-coil to create the Sparks(6 V Power Supply).As far as I can say, it should work that way:http://s7.directupload.net/file/d/3042/don2ky93_png.htm(sorry couldn't use the img-function?)My questions are:-Is the capacitor needed? I've read that they should be parallel to the coil to improve the performance?-I'm not sure about the transistor. I want to separate the ignition-circuit and the arduino circuit? Safety(for my board (: ) first.-I put a question-mark in the circuit. The idea of this ignition-system is to use the inductive voltage to create the sparks. As far as I know, these are ways higher than the original voltage. Should i put a diode there to protect the transistor?

You need to use symbols for components, not outline drawings (a 3 pin package could be anything), and organise the layout sensibly - ground at the bottom, supply rail and the top, and where possible current flow vertically through components. Component types and values should be clear and what is "?" supposed to be?

A circuit diagram or schematic follows these rules in order to be readable - its totally different from a physical layout.

I don't know a good upload service and used the first one google showed me. Do you know a bether one which u can recommend?

You could always have attached it directly to the post under the "Additional Options..." menu item when writing your post.

You might want to try Fritzing, It is a great breadboard centric layout system for creating electronic circuits. It can also be used for basic PCB design. It has a circuit diagram layout you can use as well. Best of all you can publish your fritzing files and other people can make suggestion and modifications directly to them.